One-piece sheet metal evaporator



July 7, 1936. D. P. H ATH ONE-PIECE SHEET METAL EVKPORATOR Original Filed June 12, 1931 A TTORNE Y Patented July 7, 1936 UNITED STATES PATENT OFFICE Application June 12, 1931, Serial No. 543,931 Renewed October 5, 1935 8 Claims.

My invention relates to sheet metal receptacles, particularly to thin walled pressure vessels forming a plurality of sides of a space for fluids or solids which are placed in heat-exchange relationship with fluids contained in the sheetmetal receptacle.

One of the objects of my invention is to provide a receptacle formed from a single sheet with corrugated passageways by continuing portions of the sheet contiguous with corregated portions of the sheet and fixing together contacting portions between the corrugations and at the edges of the sheet to form a fluid-tight vessel, having a plurality of sides adjacent matter from or to which heat is to be removed or added.

Another object of my invention is to provide a method of manufacture by which condensers, evaporators and boilers may economically be made from a single sheet by embossing the sheet before or after superimposing portions of the sheet together and brazing or welding together its contiguous portions.

Another object is to provide a one-piece sheetmetal evaporator, forming four-sides of a freezing compartment, with refrigerant passageways communicating entirely around the compartment and with one or more shelves, having refrigerant contact therewith, extending into the freezing compartment to provide a more eflicient freezing means.

In the accompanying drawing,

Fig. 1 is a. perspective of a flooded system of refrigerant evaporator, constructed in accordance with my invention.

Fig. 2 is a part section in elevation along, line A -A. Fig. 1, showing a header modification.

Fig. 3 is a perspective of a receptacle showing continuous corrugations. I

Fig. 4 is a perspective of a sheet metal recep tacle showing a single wall structure.

Fig. 5 is an enlarged part section in elevation orrf' ge along the line D-D through one of the shelves and through the corrugated wall.

Referring to the drawing, an evaporator constructed in accordance with my invention is shown in Fig. l as comprising a single relatively thin sheet I, which is disposed in spaced and parallel relation with respect to the oppositely formed walls which as a whole serve as side walls and top and bottom walls of a. freezing compartment F. Portions 2 of the sheet are embossed to provide fluid communication from the side walls to the embossed header portions .4

and H at top and bottom of F. Between the embossing 2, which may be preferably corrugations, are substantially flat portions 3.

To form the closed receptacle, the sheet is bent twice around to form a sleeve having contiguous contacting peripheral edges 6, and contiguous contacting portions at 3 between the embossing, with the sheet end I lying near the sheet end 8. The edges 6, are sealed to each other at the front and back while the ends 1 and 8 are sealed to the contacting portions of I.

As hereafter described, a more efficient circulation of the liquid within the receptacle is accomplished by forming the passageways 2 near the front and back edges of the receptacle with a cross-section area that is differential in size 15 with respect to the cross-section area of the centrally located passageways 2 Also the centrally located passageways 2 may open into the header 4 at a lower level than the opening of the front and back passageways 2 to assist the liquid flow. 20

That smoother surfaces may be arranged I may provide an ofiset 5 in a central portion of sheet I to register with ends I and 8. The oilset 5 shown in Fig. 1 does not allow the passageways in one side wall to freely communicate at 5 the ends 1 and 8 to the other side wall and it is sometimes desirable to secure such a circulation entirely around the freezing chamber F, I have shown in Fig. 2 a modification of the ofiset 5 with one or more openings l4. Thus the con- 30 struction of Fig. 2'may be used to serve as the gas-liquid dome 4 at the top of the sleeve, or'it may be established at the bottom to replace headers I1 and act in conjunction with the dome 4. However, in either case free circulation about 35 the compartment is secured.

To resist structural change, due to fluid pressure, I prefer to fasten together substantial contacting areas at 3, and I have found that brazing or welding methods are to be preferred to 40 riveting or soldering.

The freezing chambers, Figs. 1 and 3, are shown in a horizontal plane, but they may also be difierently arranged.

Corrugations 9 may be formed in a portion of sheet I to serve as communication channels be-' tween passages 2 and as supports providing eflicient heat transfer conditions for trays or trayshelves, arranged for refrigerating materials placed in intimate thermo relationship therewith.

The corrugations 9 may be embossed to a considerable depth as shown in Fig. 3, without extending to the peripheries and may be designed to maintain their form under a somewhat severe pressure. However, when these portions of sheet lished by the corrugation extension of one or more portions I5, from one or more side walls opposite shelves I5 may contact and may be fused together.

Conduits I0 and II may be arranged through header 4 or between the contacting edges 8 of sheet I to extend intoia header portion, such as 4 or II, to provide inlet and outlet passages. This header 4 and corrugations 2 may be formed in the outer portion of the walls of the compartment F, in the inner portion, or complementally in both outer and inner portions of sheet I.

In the manufacture of the receptacle, a metallic sheet I is embossed with the corrugations and the offset desired and formed on a brake or rolled over a mandrel to bring the contacting portions of sheet I into a receptacle-forming position. The ends I and 8 may then be fixed to a central portion'of sheet I. Lines of spot or seam welding fix together contiguous portions of the sheet between corrugations and at the peripheries. The sealing of the receptacle is accomplished by the welding or other means.

While I prefer to first corrugate the sheet before welding, I have also found it feasible to form the desired general shape of the structure from a plain sheet and weld contiguous portions together along lines defining channels. Then after sealing the edges, fluid pressure is admitted between the welds to distend the metal so that passageways remain after the pressure is released.

Fig. 3 shows one of the many'ways of employing the invention with continuous passageways formed in the sheet. The corrugations 2 are arranged sinuously in a portion of sheet I that the series passageways resulting between the contiguous corrugated and plain portions of the sheet may be utilized with the expansion valve I6 in the dry system of refrigeration. The contiguous peripheries and the contiguous flat portions of the sheet I between corrugations are brazed or welded together as in the structure of Fig. 1, and the inlet and outlet conduits II and I0 may be welded between the portions of sheet I at the ends of the passageway 2.

In operation, any type of usual refrigerating machine may be used to remove refrigerant from and feed refrigerant into the evaporator. Re-

frigerant is admitted through conduit III in the flooded evaporator of Fig. 1 and a refrigerant liquid level is maintained in the evaporator dome to a height sufficient to allow liquid to flow from 4 into the centrally located passageways 2 and to allow a proper gas space in the gas-liquid header 4.

A liquid refrigerant in the passageways of the four walls and the shelves boils when the gas is removed by the machine. Heat from the food compartment is thus transferred from the evaporator and dissipated outside the insulated wall of the refrigerator I9.

In the preferred flooding system design as shown in Fig. 1, where passageways 2 communicate with both a top gas and liquid header 4 and bottom liquid headers, I I, the liquid circulation within the evaporator is established by the upward rise of the gas bubbles during boiling. The corrugations at the front and back portions of the evaporator attain a slightly higher temperature than the temperature of the corrugations located therebetween. Therefore. evaporation is more rapid in the front and back passageways, and the central passageways act as liquid feeders or downcomers for the liquid refrigerant flowing from 4 to I1. This path of flow is most efficiently established when one or more centrally located passageways 2', are of larger cross-sectional area than the cross sectional area' of the passageways 2 near the front and back. The effect may also be accelerated .by an insulating means such as I8, Fig. 5, placed over the central corrugation. As shown in Fig. 4 the central corrugation 2' may also open into the header 4 at a level lower than the openings of the passageways 2 which are at the front and back of the evaporator. The end of the inlet conduit IIJ may terminate adjacent to the central passageway formed by the'corrugation 2' where said passageway enters the header 4 or it may extend into said passageway to insure a downward flow of incoming liquid refrigerant to the evaporator.

In the dry system operation,'expansion valve I 6 Fig. 3, feeds liquid and gas into the sinuous coil through conduit I 0. The refrigerant machine removes expanded gas with its heat load from the other end of 2 through conduit II. Corrugation 9 may communicate with one of the passes of 2 to bring the expanding refrigerant into intimate thermo relationship with the shelves 20 and trays within F.

To operate the receptacle as a condenser for steam or gases, the fluids are admitted through conduit I0 and after condensing in the passageways 2 are drawn off at the bottom header IT or bottom outlet II.

As a result of this construction, the receptacle is formed with a minimum of joints and a very large surface for heat transfer is effectively arranged. The corrugated shelves function as heatabsorbing or heat-radiating fins more efficiently than the usual fin structure which is not in direct contact with the heat transferring fluid.

Changes in construction may be made without departing from the spirit of the invention, and I do not wish to limit myself to any particular form or arrangement of parts. The structure of Figs. 1 and 4 may also be made from a plurality of sheets.

I claim:

1. An evaporator comprising, a single embossed sheet of metal perforated at a central point and rolled continuously in one direction upon itself to form a double walled sharp freezing compartment, the ends of the sheet being contiguous with and secured to oppposite faces of the central por tion of the sheet adjacent said perforation therein, the faces of the sheet adjacent the edges thereof being in contiguous relation and being secured together to form a refrigerant expansion chamber extending continuously entirely around the walls of the freezing compartment formed by said single sheet.

2. An evaporator comprising, a single embossed sheet of metal rolled. continuously in one direction upon itself to form a double walled sharp freezing compartment, the ends of the sheet being contiguous with and secured to opposite faces of the central portion of the sheet, the faces of the sheet adjacent the edges thereof being in contiguous relation and being secured together 76 to form a refrigerant expansion chamber between the double walls formed by said single sheet, contiguous portions of said sheet adjacent embossed portions thereof being secured together to in- 5 crease the structural strength of the walls of the evaporator, and the inner sheet metal portion of the double wall having inwardly directed reverse bent portions providing a refrigerated support within the compartment and dividing said J compartment into a plurality of sharp freezing compartments.

3. An evaporator comprising, a single embossed sheet of metal rolled continuously in one direction upon itself to form a double walled sharp i freezing compartment, the ends of the sheet being contiguous with and secured at a predetermined pointto oppposite faces of the sheet, the

faces of the sheet adjacent the edges thereof being in contiguous relation and being secured I together to form a refrigerant expansion chamber between the double walls formed by said single sheet, contiguous portions of said sheet adjacent embossed portions thereof being secured together to divide said refrigerant expansion chamber into i a plurality of refrigerant expansion passages and to increase the structural strength of the walls of the evaporator, and the inner sheet metal portion of the double wall having inwardly directed reverse bent portions providing a refrigerated support-within the compartment and dividing said compartment into a plurality of sharp freezing compartments. I

4. An evaporator comprising, a single embossed sheet of metal perforated at a predetermined point and rolled continuously in one direction upon itself to form a double walled sharp freezing compartment, the ends .of the sheet being contiguous with and secured to opposite faces of the portion of the sheet adjacent said perforation therein,

' the faces of the sheet adjacent the edges thereof being in contiguous relation and being secured together to form a refrigerant expansion chamber extending continuously entirely around the v walls of the freezing compartment formed by said single sheet.

5. An evaporator comprising, a single embossed sheet of metal perforated at a predetermined point and rolled continuously in one direction upon itself to form a double walled sharp freezing compartment. the ends of the sheet being contiguous with and secured to opposite faces of the portions of the sheet adjacent said perforation therein, the faces of the sheet adjacent the edges thereof being in contiguous relation and being securedtogether to form a refrigerant expansion chamber extending continuously entirely around the walls of the freezing compartment formed by said single sheet, and contiguous portions of said sheet adjacent embossed portions thereof being secured together to divide said refrigerant expansion chamber into a plurality of refrigerant expansion passages and to increase the structural strength .of the walls of the evaporator.

6. An evaporator comprising, a single embossed sheet of metal perforated at a predetermined point and rolled continuously in one direction upon itself to form a double walled sharp freezing compartment, the ends of the sheet being 5 contiguous with and secured to opposite faces of the portion of the sheet adjacent said perforation therein, the faces of the'sheet adjacent the edges thereof being in contiguous relation and being secured together to form a refrigerant expansion chamber extending continuously entirely around the walls of the freezing compartment formed by said single sheet, and the inner sheet metal portion of the double wall having inwardly directed reverse bent portions providing a refrigerated support within the compartment and dividing said compartment into a plurality of sharp freezing compartments.

7. An evaporator comprising, a single sheet of metal rolled continuously in one direction upon itself to form a double walled sharp freezing chamber, the ends of the sheet being contiguous with and secured at a predetermined point to opposite faces of the sheet, the faces of the sheet adjacent the edges thereof and along one wall of the sharp freezing chamber being spaced apart to form a header or manifold between the double walls, the faces of the sheet adjacent the edges thereof having certain parts spaced apart and certain other parts thereof secured together to increase the structural strength of the walls of the evaporator and to form a plurality of refrigerant passages betweenthe double walls communieating with said header or manifold and extending outwardly therefrom over certain walls of the freezing chamber, and the inner sheet metal por tion of the double wall having inwardly directed reverse bent portions providing a refrigerated support within the chamber and dividing said chamber into a plurality of sharp freezing compartments.

8. An-evaporator comprising, a single embossed sheet of metal rolled continuously in one direction upon itself to form adouble walled freezing chamber, the ends of the sheet being contiguous with and secured at a predetermined point to vopposite faces of the sheet, the faces of the sheet adjacent the edges thereof being in contiguous relation and being secured together to form a refrigerant expansion chamber between the double walls formed by said single sheet, contiguous portions of said sheet adjacent embossed portions thereof being secured together to divide said refrigerantexpansion chamber into a plurality of refrigerant expansion passages and to increase the structural strength of the walls of the evaporator, and the inner sheetmetal portion of the double wall having an inwardly directed reverse bent portion providing a refrigerated support within the freezing chamber and dividing the freezing chamber into a plurality of sharp freezing compartments.

Dams P. mm 

